Add native menu for mac and refactor MainWindow

Source/LibationAvalonia/ViewModels/MainVM.Export.cs

@@ -0,0 +1,74 @@
+using ApplicationServices;
+using Avalonia.Platform.Storage;
+using FileManager;
+using LibationFileManager;
+using System;
+using System.Threading.Tasks;
+
+namespace LibationAvalonia.ViewModels
+{
+	partial class MainVM
+	{
+		private void Configure_Export() { }
+
+		public async Task ExportLibraryAsync()
+		{
+			try
+			{
+				var options = new FilePickerSaveOptions
+				{
+					Title = "Where to export Library",
+					SuggestedStartLocation = await MainWindow.StorageProvider.TryGetFolderFromPathAsync(Configuration.Instance.Books.PathWithoutPrefix),
+					SuggestedFileName = $"Libation Library Export {DateTime.Now:yyyy-MM-dd}",
+					DefaultExtension = "xlsx",
+					ShowOverwritePrompt = true,
+					FileTypeChoices = new FilePickerFileType[]
+					{
+						new("Excel Workbook (*.xlsx)")
+						{
+							Patterns = new[] { "*.xlsx" },
+							//https://gist.github.com/RhetTbull/7221ef3cfd9d746f34b2550d4419a8c2
+							AppleUniformTypeIdentifiers = new[] { "org.openxmlformats.spreadsheetml.sheet" }
+						},
+						new("CSV files (*.csv)")
+						{
+							Patterns = new[] { "*.csv" },
+							AppleUniformTypeIdentifiers = new[] { "public.comma-separated-values-text" }
+						},
+						new("JSON files (*.json)")
+						{
+							Patterns = new[] { "*.json" },
+							AppleUniformTypeIdentifiers = new[] { "public.json" }
+						},
+						new("All files (*.*)") { Patterns = new[] { "*" } }
+					}
+				};
+
+				var selectedFile = (await MainWindow.StorageProvider.SaveFilePickerAsync(options))?.TryGetLocalPath();
+
+				if (selectedFile is null) return;
+
+				var ext = FileUtility.GetStandardizedExtension(System.IO.Path.GetExtension(selectedFile));
+				switch (ext)
+				{
+					case ".xlsx": // xlsx
+					default:
+						LibraryExporter.ToXlsx(selectedFile);
+						break;
+					case ".csv": // csv
+						LibraryExporter.ToCsv(selectedFile);
+						break;
+					case ".json": // json
+						LibraryExporter.ToJson(selectedFile);
+						break;
+				}
+
+				await MessageBox.Show("Library exported to:\r\n" + selectedFile, "Library Exported");
+			}
+			catch (Exception ex)
+			{
+				await MessageBox.ShowAdminAlert(MainWindow, "Error attempting to export your library.", "Error exporting", ex);
+			}
+		}
+	}
+}